[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Abandon the (mistaken) belief that XML attributesprovide "
On Sun, 2011-03-20 at 17:51 -0400, John Cowan wrote: > Liam R E Quin scripsit: > > > The more abstract pattern is that Schema has avoided the idea of a > > descendent changing the meaning of an element. > > Rather, of changing its content model -- not the same thing. I was deliberately vague about meaning - for XSD it's not only about content models. Indeed, conditional type assignment and unions are both steps in the direction of a content model (in the DTD sense) depending on children. Perhaps a clearer example might be SimpleType vs ComplexType - it would be possible just to use Type, and say that e.g. if there's an attribute defined, it's a complex type. But there are lots of additional constraints on where complex types can appear that would then become much harder to understand. And, of course XSLT/XPath/XQuery/XForms would have problems... Or, in C, short s = (65535 + 17); on a system where short is 16-bit, doesn't declare a sufficiently large variable to hold the value :-) I think we are actually probably agreeing, but I am trying to find alternate expressions to be clearer. To go back to attributes, some people have strong aversion to syntax like, <p> <attributes> <attribute> <name>type</name> <value>body_t</value> </attribute> <attribute> <name>id</name <type>xml:id</type> <value>p16</value> </attribute> </attributes> <content>Hello world</content> </p> rather than <p type="body_t" xml:id="p16">Hello world</p> and not only because of verbosity but because of the children-affecting-parents nature. Since I'm not myself strongly in that camp, I might be misrepresenting it a little; I'd be perfectly happy to see <xml:attributes> as an alternate syntax, as it happens, in some putative world in which everyone immediately rewrote all their XML APIs... Best, Liam -- Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/ Pictures from old books: http://www.fromoldbooks.org/ Occasional blog: http://www.barefootliam.org/ The barefoot typographer
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